Magnetron plasma processing apparatus

ABSTRACT

A magnetron plasma processing apparatus has a baffle plate interposed between a processing space and a gas exhaust port so as to confine a plasma in the processing space in a processing chamber. The baffle plate has through holes allowing the processing space and the gas exhaust port to communicate with each other. The baffle plate is provided along lines of magnetic force of a magnetic field at a position where the plate is located.

This application is a Continuation-In-Part of PCT InternationalApplication No. PCT/JP03/07802 filed on Jun. 19, 2003, which designatedthe United States.

FIELD OF THE INVENTION

The present invention relates to a magnetron plasma processing apparatusfor performing a semiconductor processing such as a magnetron etching orthe like on a substrate to be processed, e.g., a semiconductor wafer orthe like. The term “semiconductor processing” used herein impliesvarious processes to manufacture semiconductor devices and/or astructure including wiring, electrodes, and the like connected to thesemiconductor devices on a substrate to be processed, e.g., asemiconductor wafer or an LCD substrate, by forming thereon asemiconductor layer, an insulating layer, a conductor layer, and thelike, in a predetermined pattern.

BACKGROUND OF THE INVENTION

In recent years, there has been utilized a magnetron plasma etchingapparatus for performing an etching in a microprocessing by producing ahigh density plasma at a relatively low pressure atmosphere. In thisapparatus, an RF (high frequency) electric field is formed inside aprocessing space such that electric lines of force vertically penetrate(i.e., an electric field direction is perpendicular to) a semiconductorwafer. In the specification, the term “vertical direction” refers to adirection of gravity. Further, in the processing space, a magnetic fieldis formed by a permanent magnet such that magnetic force lines arenormal to the electric lines of force (i.e., a magnetic field directionis horizontal). By such orthogonal electric and magnetic fields, amagnetron discharge accompanied by drift motions of electrons isperformed, so that an etching can be carried out with very highefficiency.

As an example of a magnet for use in the magnetron plasma etchingapparatus, there is a dipole ring magnet. The dipole ring magnet has amultiplicity of columnar anisotropic magnet segments disposed in a ringshape around a processing chamber. Magnetization directions of thesemagnet segments are shifted slightly with respect to each other, suchthat a uniform horizontal magnetic field is formed on the whole.

As another example of the magnet for use in the magnetron plasma etchingapparatus, there is a multi-dipole ring magnet. The multi-dipole ringmagnet has a multiplicity of magnet segments disposed in a ring shape tosurround a wafer such that N poles and S poles thereof are alternatelyarranged. The multi-dipole ring magnet forms a multi-pole magnetic fieldsurrounding the circumference of the wafer without forming a magneticfield on an upper surface of the wafer. The above-described dipolemagnetic field and multi-pole magnetic field are selectively useddepending on a process.

In a plasma processing apparatus including but not limited to themagnetron plasma etching apparatus, it is necessary to prevent a plasmafrom arriving at a lower part of the processing chamber and thus causingan abnormal discharge. For this, an annular baffle plate is installed ata downward position of the wafer between a mounting table for mountingthereon the wafer and a processing chamber wall to shut off the plasma.In other words, the baffle plate is interposed between the processingspace and a gas exhaust port to confine the plasma inside the processingspace. The baffle plate has multiple through holes allowing theprocessing space and the gas exhaust port to communicate with eachother.

However, as will be explained below, an abnormal discharge or a plasmaleak toward a downside of the baffle plate disposed as mentioned aboveis observed in a conventional magnetron plasma etching apparatus,according to a study of the present inventors.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to prevent anabnormal discharge or a plasma leak towards a downside of the baffleplate, in a magnetron plasma processing apparatus.

In accordance with a first aspect of the present invention, there isprovided a magnetron plasma processing apparatus including: an airtightprocessing chamber for accommodating therein a substrate to beprocessed; a gas supply unit for supplying a processing gas into theprocessing chamber; a gas exhaust unit for exhausting an inside of theprocessing chamber and setting the inside of the processing chamber in avacuum state, the gas exhaust unit having a gas exhaust port formed at alower part of the processing chamber; an upper and a lower electrodefacing each other while having therebetween a processing space formedabove the gas exhaust port inside the processing chamber, the lowerelectrode serving as a mounting table for mounting thereon the substrateto be processed; an electric field forming unit for forming an electricfield by applying an electric power between the upper and the lowerelectrode, the electric field exciting the processing gas in theprocessing space to convert same into a plasma; a magnetic field formingunit for forming a magnetic field whose central magnetic force linesruns parallel to a radial direction of the processing chamber; and abaffle plate interposed between the processing space and the gas exhaustport such that the plasma is confined in the processing space, thebaffle plate having multiple through holes allowing the processing spaceand the gas exhaust port to communicate with each other, and the baffleplate being disposed along magnetic force lines of the magnetic field ata mounting position thereof.

In accordance with a second aspect of the present invention, there isprovided a magnetron plasma processing apparatus including: an airtightprocessing chamber for accommodating therein a substrate to beprocessed; a gas supply unit for supplying a processing gas into theprocessing chamber; a gas exhaust unit for exhausting an inside of theprocessing chamber and setting the inside of the processing chamber in avacuum state, the gas exhaust unit having a gas exhaust port formed at alower part of the processing chamber; an upper and a lower electrodefacing each other while having therebetween a processing space formedabove the gas exhaust port inside the processing chamber, the lowerelectrode serving as a mounting table for mounting thereon the substrateto be processed; an electric field forming unit for forming an electricfield by applying an electric power between the upper and the lowerelectrode, the electric field exciting the processing gas in theprocessing space to convert same into a plasma; a magnetic field formingunit for forming a magnetic field whose central magnetic force lines runparallel to a radial direction of the processing chamber; and a baffleplate interposed between the processing space and the gas exhaust portsuch that the plasma is confined in the processing space, the baffleplate having multiple through holes allowing the processing space andthe gas exhaust port to communicate with each other, wherein the throughholes are disposed to be tilted with respect to a surface of the baffleplate such that the through holes are substantially normal to magneticforce lines of the magnetic field at a mounting position of the baffleplate.

In accordance with a third aspect of the present invention, there isprovided a baffle plate being mounted to a processing chamber and amounting table of a magnetron plasma processing apparatus, the baffleplate being interposed between a processing space and a gas exhaust portof the apparatus, the baffle plate including: a truncated cone shapedmain body tilted along magnetic force lines of a magnetic field atposition where the baffle plate is mounted, the main body havingmultiple through holes allowing the processing space and the gas exhaustport to communicate with each other; an outer mounting portion formounting the main body to the processing chamber; and an inner mountingportion for mounting the main body to the mounting table.

In accordance with a fourth aspect of the present invention, there isprovided a baffle plate being mounted to a processing chamber and amounting table of a magnetron plasma processing apparatus, the baffleplate being interposed between a processing space and a gas exhaust portof the apparatus, the baffle plate including: a flat circular plateshaped main body having multiple through holes allowing the processingspace and the gas exhaust port to communicate with each other, whereinthe through holes are disposed to be tilted with respect to a surface ofthe main body such that the through holes are substantially normal tomagnetic force lines of a magnetic field at a mounting position of thebaffle plate; an outer mounting portion for mounting the main body tothe processing chamber; and an inner mounting portion for mounting themain body to the mounting table.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome apparent from the following description of preferred embodimentsgiven in conjunction with the accompanying drawings, in which:

FIG. 1 offers a cross sectional view showing a magnetron RIE plasmaetching apparatus having a dipole ring magnet, in accordance with afirst embodiment of the present invention;

FIG. 2 illustrates a horizontal cross sectional view schematicallyshowing the dipole ring magnet in the apparatus of FIG. 1;

FIG. 3 is a schematic view for explaining an electric field and amagnetic field formed inside a processing chamber of the apparatusdescribed in FIG. 1;

FIG. 4 sets forth to a perspective view showing a cutoff portion of abaffle plate in the apparatus of FIG. 1.

FIG. 5 presents a plain view showing a part of the baffle plate in theapparatus of FIG. 1;

FIG. 6 provides a cross sectional view showing a magnified mountingstate of the baffle plate in the apparatus of FIG. 1;

FIG. 7A describes a schematic view showing a relationship between thebaffle plate in accordance with the first embodiment and magnetic forcelines;

FIG. 7B depicts a schematic view showing a relationship between aconventional baffle plate and magnetic force lines;

FIG. 8A shows a relationship between a simulation result of a magneticfield direction and a conventional baffle plate;

FIG. 8B describes a relationship between a simulation result of amagnetic field direction and a baffle plate in accordance with the firstembodiment;

FIG. 9 is a schematic view showing a relationship between a baffle plateand magnetic force lines in a magnetron RIE plasma etching apparatus inaccordance with a second embodiment of the present invention; and

FIG. 10 illustrates a horizontal cross sectional view schematicallyshowing a multi-dipole ring magnet.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the process of developing the present invention, the inventorsstudied a conventional magnetron plasma etching apparatus wherein abaffle plate is placed between a processing space and a gas exhaustport. As a result, a knowledge as discussed below could be obtained.

In a magnetron plasma processing apparatus such as a magnetron plasmaetching apparatus, a baffle plate is generally installed below amounting position of a wafer. Thus, magnetic force lines of a magneticfield pass through the baffle plate at a slant. Since electrons spirallymove along the magnetic force lines, the electrons easily pass thethrough holes as an angle formed by the through holes of the baffleplate and the magnetic force lines gets small. For the same reason, inthe conventional magnetron plasma processing apparatus, it is consideredthat the baffle plate cannot shut off the plasma sufficiently, whichcauses the plasma leak towards a downside of the baffle plate or theabnormal discharge.

Hereinafter, preferred embodiments of the present invention, which areconfigured based on such a knowledge, will be explained with referenceto the accompanying drawings. In the following explanation, parts havingsubstantially the same functions and configurations are designated bythe same reference numerals, and their redundant explanations will beomitted unless necessary.

FIG. 1 is a cross sectional view showing a magnetron RIE plasma etchingapparatus having a dipole ring magnet in accordance with a firstembodiment of the present invention. This etching apparatus has anairtight processing chamber (processing vessel) 1. The processingchamber 1 is of a stepped cylindrical shape formed of an upper part 1 aof a small diameter and a lower part 1 b of a large diameter. Theprocessing chamber 1 is made of, e.g., aluminum whose surface isalumite-treated, and grounded.

Inside the processing chamber 1, there is installed a mounting table 2horizontally supporting a wafer W, i.e., a substrate to be processed.The mounting table 2 also serves as a lower electrode. The mountingtable 2 has a core member 2 a made of, e.g., aluminum; an insulationmember 3 covering a sidewall and a bottom part of the core member 2 a;and a supporting base 4 made of a conductor for supporting the coremember 2 a and the insulation member 3. As shown in FIG. 6, theinsulation member 3 is divided into three members 3 a, 3 b and 3 c.

On a top surface of the mounting table 2, there is disposed anelectrostatic chuck 6 for electrostatically adsorbing and supporting thewafer W. The electrostatic chuck 6 is made of an insulator havingtherein an electrode 6 a. The electrode 6 a is connected to a DC powersupply 16, which applies thereto a voltage, to thereby adsorb the waferW by an electrostatic force, e.g., Coulomb force. A focus ring 5 isplaced around the electrostatic chuck 6 on the mounting table 2. The topsurface of the wafer W adsorbed to the electrostatic chuck 6 coincideswith that of the focus ring 5.

A coolant chamber 17 is formed inside the core member 2 a of themounting table 2. In the coolant chamber 17, a coolant is circulated insuch a manner that it is introduced via a coolant introduction line 17 aand discharged from a coolant discharge line 17 b. A cold heat from thecoolant is transferred to the wafer W via the mounting table 2, so thata processing surface of the wafer W is controlled at a desiredtemperature. Further, a heat transfer gas, e.g., He gas, is introducedbetween a surface of the electrostatic chuck 6 and a rear surface of thewafer W via a gas supply line 19 by a gas introduction mechanism 18. Inthis way, even though the processing chamber 1 is exhausted by a gasexhaust unit 12 and maintained in a vacuum state, a heat transferbetween the electrostatic chuck 6 and the wafer W is maintained.Therefore, the wafer W can be efficiently cooled by the coolantcirculated in the coolant chamber 17.

The mounting table 2 can be elevated by a ball screw mechanismcontaining ball screws 7. A driving part at a lower part of thesupporting base 4 is covered with a bellows 8 made of a stainless steel(SUS). A bellows cover 9 is installed outside the bellows 8.

A truncated cone shaped baffle plate 10 is disposed below the wafer Wbetween the mounting table 2 and an inner wall of the processing chamber1. The baffle plate 10 is fitted to an attachment member 24 of an outerperiphery of the mounting table 2 and to the processing chamber 1, andis grounded via the processing chamber 1. The baffle plate 10 will bediscussed later in detail.

On a sidewall of the lower part 1 b of the processing chamber 1, a gasexhaust port 11 is installed and connected to the gas exhaust unit 12.By operating a vacuum pump of the gas exhaust unit 12, an inside of theprocessing chamber 1 is exhausted and depressurized to a predeterminedvacuum level. Meanwhile, in an upper side of the sidewall of the lowerpart 1 b of the processing chamber 1, there is installed a gate valve 13opening/closing a loading/unloading part of the semiconductor wafer W.

An RF (high frequency) power supply 15 for producing a plasma isconnected to the mounting table 2 via a matching unit 14. An RF powerhaving a predetermined frequency of 13.56 MHz or greater (e.g., 13.56MHz or 40 MHz) is supplied to the mounting table 2 from the RF powersupply 15. Meanwhile, a showerhead 20 is disposed in parallel with themounting table 2, i.e., facing the mounting table 2. The showerhead 20serves as an upper electrode and is grounded. Therefore, the mountingtable 2 serving as the lower electrode and the showerhead 20 serving asthe upper electrode comprises a pair of parallel plate electrodes

The showerhead 20 is formed as a ceiling wall part of the processingchamber 1. A head space 21 is formed inside the showerhead 20. At alower surface of the showerhead 20, there are formed a plurality of gasdischarge holes 22 communicating with the head space 21. A gas inlet 20a communicating with the head space 21 is formed in a upper part of theshowerhead 20. A processing gas supply unit 23 for supplying apredetermined processing gas is connected to the gas inlet 20 a via thegas supply line 23 a.

The processing gas is supplied from the processing gas supply unit 23into the head space 21 of the showerhead 20 via the gas supply line 23 aand the gas inlet 20 a. Then, the processing gas is uniformly dischargedin the processing chamber 1 through the gas discharge holes 22. As theprocessing gas supplied from the processing gas supply unit 23, ahalogen based gas, an Ar gas, an O₂ gas or the like, which is commonlyused in this field, may be utilized.

Around the upper part 1 a of the processing chamber 1, a dipole ringmagnet 30 is horizontally placed such that central magnetic force linesof a magnetic field are disposed above the baffle plate 10, e.g., thecentral magnetic force lines coincide with the top surface of the waferW on the mounting table 2. The dipole ring magnet 30 is rotated in ahorizontal plane by a rotation mechanism 35.

FIG. 2 is a horizontal cross sectional view schematically showing thedipole ring magnet 30. As shown in FIG. 2, the dipole ring magnet 30 isconfigured such that a multiplicity of columnar anisotropic magnetsegments 31 are attached to a ring shaped casing 32 of a magneticmaterial. In this example, sixteen columnar anisotropic magnet segments31 forming a columnar shape are arranged in a ring shape. In FIG. 2,arrows shown in the magnet segments 31 indicate magnetizationdirections. As shown in FIG. 2, the magnetization directions of themagnet segments 31 are shifted slightly with respect to each other, suchthat a uniform horizontal magnetic field B heading for one direction onthe whole is formed above the wafer W

FIG. 3 is a schematic view for explaining an electric field and amagnetic field formed inside the processing chamber 1. As shown in FIG.3, in a processing space S between the mounting table 2 and theshowerhead 20, an RF electric field E of a vertical direction is formedby an RF power applied from the RF power supply 15 to the mounting table2. Further, in the processing space S, a horizontal magnetic field B isformed above the wafer W by the dipole ring magnet 30. By the orthogonalelectric and magnetic fields as formed above, the magnetron discharge iscarried out, whereby a plasma of an etching gas of a high energy stateis produced and a predetermined film on the wafer W is etched.

In the following, the baffle plate 10 will be explained in detail. FIG.4 is a perspective view showing a cutoff portion of the baffle plate 10.FIG. 5 is a plain view showing a part of the baffle plate 10. FIG. 6 isa cross sectional view showing a magnified mounting state of the baffleplate 10.

The baffle plate 10 is formed by thermally spraying ceramics, e.g.,alumina, on a metal, e.g., aluminum, to increase plasma resistance. Thebaffle plate 10 has in a center thereof a circular hole into which themounting table is inserted, and has a truncated cone shaped main body 10a having thereon multiple circular gas passing holes (through holes) 10b. An outer mounting portion 10 c is formed at an outer peripheralportion of the main body 10 a, which is fitted into a cutout portion 1 d(see FIG. 6) of an attachment fixture 1 c of the processing chamber 1.An inner mounting portion 10 d is formed at an inner peripheral portionof the main body 10 a, and mounted on an attachment member 24 around themounting table 2.

The outer mounting portion 10 c has bolt insertion holes 10 e. The outermounting portion 10 c and the attachment fixture 1 c of the processingchamber are engaged by multiple bolts 25 inserted from the upper part ofthe processing chamber 1. Meanwhile, the inner mounting portion 10 d hasbolt insertion holes 10 f. The inner mounting portion 10 d and theattachment member 24 are engaged by bolts 26.

Since the main body 10 a has a truncated cone shape as mentioned above,the baffle plate 10 is tilted upward with an angle θ from a central sidetowards an end side, in its vertical cross sectional view. In this case,the angle θ is set to be substantially equal to a tilt angle of themagnetic field (a tilt angle of the magnetic force lines passing thebaffle plate 10) when viewed with respect to the mounted baffle plate10, as shown in FIG. 7. For example, the angle θ is set as 10˜45degrees.

A diameter and an aspect ratio of the gas passing hole 10 b aredetermined such that the plasma is not likely to penetrate therethroughand the exhaust conductance can be secured sufficiently. For example,the diameter is set as 1.7 mm and a height (i.e., a thickness of thebaffle plate 10) is set as 3 mm. A shape of the gas passing hole 10 b isnot limited to a circle, but may be of an elliptic or a slit shape.

In other words, the baffle plate 10 is interposed between the processingspace S and the gas exhaust port 11 such that the plasma is confinedinside the processing space S. The baffle plate 10 is mounted to bedisposed along the magnetic force lines of the magnetic field. Thebaffle plate 10 has multiple gas passing holes (through holes) 10 ballowing the processing space S and the gas exhaust port 11 tocommunicate with each other. As shown in FIG. 6, the gas passing holes10 b are formed substantially normal to the front and rear surfaces ofthe baffle plate 10. Thus, the gas passing holes 10 b are placedsubstantially normal to the magnetic force lines of the magnetic fieldat the mounting position of the baffle plate 10.

Next, an operation of the magnetron RIE plasma etching apparatus asconfigured above will be discussed.

First, the wafer W is loaded into the processing chamber 1 by openingthe gate valve 13 and mounted on the mounting table 2. Subsequently, apredetermined voltage is applied to the electrode 6 a of theelectrostatic chuck 6 from the DC power supply 16, so that the wafer Wis kept adsorbed onto the electrostatic chuck 6 by coulomb force. Then,the mounting table 2 is elevated to a position indicated in FIG. 1. Theinside of the processing chamber 1 is then exhausted through the gasexhaust port 11 by a vacuum pump of the gas exhaust unit 12.

Thereafter, a predetermined processing gas for etching is introducedinto the processing chamber 1 from the gas supply unit 23 whileexhausting the inside of the processing chamber 1, so that an innerpressure of the processing chamber is maintained at, e.g., about1.33˜13.3 Pa. Further, a predetermined RF power of 13.56 MHz or greateris supplied into the mounting table 2 from the RF power supply 15. Inthis way, an RF electric field is formed between the showerhead 20 asthe upper electrode and the mounting table 2 as the lower electrode.

At this time, a horizontal magnetic field B is formed above the wafer Wby the dipole ring magnet 30. Hence, orthogonal electric and magneticfields are formed in the processing space S where the wafer W exists,between the electrodes, and a magnetron discharge is caused by theresultant electron drift. Further, a predetermined film on the wafer isetched by the plasma of the etching gas produced by the magnetrondischarge.

FIG. 7A is a schematic view showing a relationship between the baffleplate in accordance with the first embodiment and magnetic force lines.FIG. 7B is a schematic view showing a relationship between theconventional baffle plate and magnetic force lines. As shown in FIGS. 7Aand 7B, in the horizontal magnetic field heading for one direction,which is formed by the dipole ring magnet 30, the direction of themagnetic force lines on the top surface of the wafer W becomeshorizontal, in the vertical cross sectional view. However, as thehorizontal magnetic field goes apart from the wafer W along the verticaldirection, vertical components thereof increase.

In such a situation, a relationship between the baffle plate 10C andmagnetic force lines MFL is as shown in FIG. 7B, in case of the baffleplate 10C horizontally disposed in a same way as in the conventionalart. Namely, the baffle plate 10 is of a flat circular plate shape andhorizontally placed regardless of the direction of the magnetic forcelines MFL. Through holes 10Cb of the baffle plate are formed to besubstantially normal to the front and rear surfaces of the baffle plate10C.

Therefore, in a state described in FIG. 7B, the magnetic force lines MFLpass through the baffle plate 10C at a slant. Further, relatively plentyof vertical components of the magnetic field exist when viewed withrespect to the mounting position of the baffle plate 10C. Electronseasily pass the through holes 10Cb as the angle formed by the throughhole 10Cb of the baffle plate and the magnetic force line MFL getssmall, since the electrons spirally move along the magnetic force linesMFL. Thus, since the baffle plate 10C cannot shut off the plasmasufficiently in the conventional magnetron plasma processing apparatus,the plasma leak towards a downside of the baffle plate 10C or theabnormal discharge is generated.

Contrary to this, in case of the baffle plate 10 in accordance with thefirst embodiment, a relationship between the baffle plate 10 and themagnetic force lines MFL is as shown in FIG. 7A. That is, the baffleplate 10 is of a truncated cone shape, and is tilted upward in anoutward the radial direction along the magnetic force lines MFL. Thethrough holes 10 b of the baffle plate are formed to be substantiallynormal to the front and rear surfaces of the baffle plate 10.

Accordingly, in a state shown in FIG. 7A, the magnetic force lines MFLpass the baffle plate 10 in parallel with each other. Further, there isfew or no vertical components of the magnetic field at the mountingposition of the baffle plate 10. Thus, the electrons spirally movingalong the magnetic force lines MFL hardly pass the through holes 10 bformed in the baffle plate, so that an effect of blocking the plasma canbe enhanced. Therefore, the plasma leak or the abnormal discharge can beprevented.

Further, the baffle plate 10 is of a truncated cone shape and tiltedupward in an outward radial direction along the magnetic force linesMFL, so that an area of the baffle plate 10 becomes larger. Therefore,more gas passing holes (through holes) 10 b can be formed in the baffleplate 10, compared with the conventional flat circular plate shapedbaffle plate 10C. By employing such a configuration, exhaust conductancebetween the processing space S and the gas exhaust port 11 can beimproved.

It is preferable that the tilt angle θ of the baffle plate 10 issubstantially equal to a tilt angle in the vertical direction of themagnetic force lines passing therethrough, i.e., a tilt angle in thevertical direction of the magnetic field at the mounting position of thebaffle plate 10. Due to this, vertical components of the magnetic fieldwith respect to the baffle plate 10 are substantially removed and thusthe effect of blocking the plasma can be further increased.

In the ensuing discussion, a result of an optimum arrangement of thebaffle plate, which was obtained by the simulation of the magnetic fielddirection, will be discussed. Here, a magnetic flux density in a centerof the wafer was set to 0.012 T (120 Gauss), in the apparatus for a 300mm wafer. FIG. 8A shows a relationship between a simulation result of amagnetic field direction and the conventional baffle plate 10C. FIG. 8Bdescribes a relationship between a simulation result of a magnetic fielddirection and the baffle plate 10 in accordance with the firstembodiment.

FIG. 8A describes a case where the baffle plate 10C is horizontallyplaced such that a vertical position of the top surface of the wafer isgiven as Z=0, and a center of a thickness thereof becomes Z=−50 (mm). Inthis case, since the vertical components of the magnetic field arerelatively large at the mounting position of the baffle plate 10C, itcan be noted that the effect of blocking the plasma is small. Incontrast, if the central side part of the baffle plate 10 is tilteddownward and θ is set to 3.85°, the tilt angle thereof becomessubstantially equal to that of the magnetic field.

Based on these results, a truncated cone shaped baffle plate having sucha tilt angle was manufactured actually. Further, a magnetron plasma testwas conducted by mounting the manufactured baffle plate in theapparatus. As a result, it is conformed that the plasma leak and theabnormal discharge are hardly generated at a lower part of the baffleplate.

FIG. 9 is a schematic view showing a relationship between a baffle plateand magnetic force lines, in a magnetron RIE plasma etching apparatus inaccordance with a second embodiment of the present invention. In theapparatus of this embodiment, parts other than a baffle plate aresubstantially equal to those of the apparatus the previously describedembodiment shown in FIG. 1 of.

In the second embodiment, like the previous embodiment, a baffle plate10X is interposed between the processing space S and the gas exhaustport 11 (see FIG. 1) such that the plasma is confined in the processingspace S. In the baffle plate 10X, multiple gas passing holes (throughholes) 10Xb are formed to allow the processing space S and the gasexhaust port 11 to communicate with each other. Further, the baffleplate 10X has the substantially same shape as that of FIG. 1 (byemploying the outer mounting portion 10 c and the inner mounting portion10 d), which is fitted to the processing chamber 1 and the mountingtable 2. Still further, the baffle plate 10X is formed by thermallyspraying ceramics, e.g., alumina, on a metal, e.g., aluminum, in orderto increase plasma resistance.

The baffle plate 10X is of a flat circular plate shape and horizontallyplaced regardless of the direction of the magnetic force lines of themagnetic field at the mounting position thereof. However, the gaspassing holes (through holes) 10Xb are configured to be tilted withrespect to the front and rear surfaces of the baffle plate 10X such thatthey are substantially normal to the magnetic force lines of themagnetic field at the mounting position of the baffle plate 10X. Thus,the electrons spirally moving along the magnetic force lines hardly passthe through holes 10Xb formed in the baffle plate, so that the effect ofblocking the plasma can be enhanced. Therefore, the plasma leak or theabnormal discharge can be prevented. Here, the through holes 10Xb areformed to have an angle, e.g., 45˜80 degree, with respect to the frontand rear surfaces of the baffle plate 10X.

Further, in accordance with the second embodiment, the baffle plate 10Xis not necessarily horizontal, and it is a primary feature thereof thatthe gas passing holes (through holes) 10Xb are formed to be tilted suchthat they are substantially normal to the magnetic force lines of themagnetic field at the mounting position of the baffle plate 10X. A shapeof each gas passing hole 10Xb is not limited to a circle, but may be ofan elliptic or a slit shape.

The present invention is not limited to the aforementioned embodimentsbut various changes thereof may be made. For example, a multi-pole ringmagnet forming a magnetic field around the wafer, i.e., in the vicinityof an inner wall of the processing chamber, may be used as a magneticfield generation means, instead of the dipole ring magnet. FIG. 10 is ahorizontal cross sectional view schematically showing a multi-pole ringmagnet 40. The multi-pole ring magnet 40 has a multiplicity of magnetsegments 42 placed in a ring shape around the processing chamber 1 suchthat N poles and S poles are alternately arranged (such that the poledirections are alternately reversed). The multi-pole ring magnet 40forms a multi-pole magnetic field, and magnetic flux densities thereofare, e.g., about 0.02˜0.2 T (200˜2000 Gauss) in the inner wall surfaceof the processing chamber 1 and about 0.0005 T (5 Gauss) in the centralpart of the wafer W. In this case, the baffle plate may be disposedalong the magnetic force line of the multi-pole magnetic field formedaround the wafer, according to the shape shown in FIG. 7A.Alternatively, according to the shape shown in FIG. 9, the gas passingholes of the baffle plate may be formed such that they are tilted to benormal to the magnetic force lines of multi-pole magnetic field.

Further, in the above-described embodiments, it is configured such thatthe processing chamber is of a columnar shape; the mounting table is ofa columnar shape; and the baffle plate is of a truncated cone shape or aflat circular plate shape. However, the baffle plate may adopt variousshapes depending on the shapes of the processing chamber and themounting table.

Still further, in the aforementioned embodiments, examples of applyingthe present invention to the magnetron plasma etching apparatus havebeen described. However, the present invention may be applied to otherplasma processes. For instance, the present invention may be applied toa magnetron plasma CVD apparatus by changing the processing gas from theetching gas to any well-known CVD gas. Further, by placing a targetinside the processing chamber to face the substrate to be processed, itmay be applied to a magnetron plasma sputtering apparatus. Meanwhile, asthe substrate to be processed, any substrate other than thesemiconductor wafer, e.g., a substrate for a liquid crystal display(LCD) or the like, may be used.

While the invention has been shown and described with respect to thepreferred embodiments, it will be understood by those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

1. A magnetron plasma processing apparatus comprising: an airtightprocessing chamber for accommodating therein a substrate to beprocessed; a gas supply unit for supplying a processing gas into theprocessing chamber; a gas exhaust unit for exhausting an inside of theprocessing chamber and setting the inside of the processing chamber in avacuum state, the gas exhaust unit having a gas exhaust port formed at alower part of the processing chamber; an upper and a lower electrodefacing each other while having therebetween a processing space formedabove the gas exhaust port inside the processing chamber, the lowerelectrode serving as a mounting table for mounting thereon the substrateto be processed; an electric field forming unit for forming an electricfield by applying an electric power between the upper and the lowerelectrode, the electric field exciting the processing gas in theprocessing space to convert same into a plasma; a baffle plateinterposed between the processing space and the gas exhaust port suchthat the plasma is confined in the processing space, wherein the baffleplate includes a main body having multiple through holes allowing theprocessing space and the gas exhaust port to communicate with each otherand a mounting portion for mounting the main body in the processingchamber; and a magnetic field forming unit for forming a magnetic field,wherein the magnetic field includes central magnetic force lines runningparallel to a top surface of the substrate mounted on the mounting tableand magnetic force lines, which pass through the main body of the baffleplate and are tilted with respect to the central magnetic force lines,and wherein the main body of the baffle plate is disposed substantiallyparallel to the magnetic force lines passing therethrough.
 2. Themagnetron plasma processing apparatus of claim 1, wherein the main bodyof the baffle plate is placed below the central magnetic force lines ofthe magnetic field and is tilted upward in an outward radial directionalong the magnetic force lines passing therethrough; and the throughholes are formed substantially normal to a surface of the main body atwhich openings of the through holes are formed.
 3. The magnetron plasmaprocessing apparatus of claim 1, wherein the main body of the baffleplate has a truncated cone shape and the through holes are formedsubstantially normal to a surface of the main body at which openings ofthe through holes are formed.
 4. The magnetron plasma processingapparatus of claim 1, wherein the through holes are of a circular, anelliptic or a slit shape.
 5. The magnetron plasma processing apparatusof claim 1, wherein the magnetic field forming unit has a dipole ringmagnet formed by arranging a multiplicity of anisotropic magnet segmentsin a ring shape around the processing chamber.
 6. The magnetron plasmaprocessing apparatus of claim 1, wherein the magnetic field forming unithas a multi-pole ring magnet formed by arranging a multiplicity ofmagnet segments in a ring shape around the processing chamber, themultiplicity of magnet segments being arranged such that pole directionsare alternately reversed.
 7. The magnetron plasma processing apparatusof claim 1, wherein a tilt angle between the central magnetic forcelines and the magnetic force lines passing through the main body of thebaffle plate is about 10 to 45 degrees.
 8. A baffle plate for use in aprocessing chamber of a magnetron plasma processing apparatus, thebaffle plate being interposed between a processing space and a gasexhaust port of the apparatus, the baffle plate comprising: a truncatedcone shaped main body tilted substantially parallel to magnetic forcelines of a magnetic field passing therethrough, the main body havingmultiple through holes allowing the processing space and the gas exhaustport to communicate with each other, the through holes being formedsubstantially normal to a surface of the main body at which openings ofthe through holes are formed; an outer mounting portion for mounting themain body to the processing chamber; and an inner mounting portion formounting the main body to the mounting table.
 9. The baffle plate ofclaim 8, wherein a tilt angle of the main body is set as 10 to 45degrees.
 10. The baffle plate of claim 8, wherein the through holes areof a circular, an elliptic or a slit shape.
 11. The baffle plate ofclaim 8, wherein the magnetic field includes central magnetic forcelines running parallel to a top surface of a substrate mounted on themounting table and the magnetic force lines passing through the mainbody of the baffle plate and wherein the magnetic force lines passingthrough the main body of the baffle plate are tilted with respect to thecentral magnetic force lines.